1. Field of the Invention
The present invention relates to an optical device having a light guide member and an optical element.
2. Description of the Related Art
For example, Jpn. Pat. Appln. KOKAI Publication No. 2007-188059 discloses an optical component that can be mounted on an end of a light guide member. In the optical component, a cap (holder) has an arrangement portion including a first fitting portion formed as a hole into which a ferrule is fitted and a second fitting portion formed as a hole communicatively connected to the first fitting portion (hole).
An optical fiber is inserted into the ferrule. The ferrule is fixed to the holder by at least one part of the side face of the ferrule being YAG-welded to the first fitting portion. Incidentally, the ferrule can be fixed to the holder by an adhesive, resistance welding, press-fitting, caulking or the like. The ferrule can also be fixed to the holder at an end of the ferrule.
An optical element (light conversion member) is disposed in the second fitting portion. The optical element is fixed to the holder by the optical element being fixed to the second fitting portion by melting-point glass or resin.
In Jpn. Pat. Appln. KOKAI Publication No. 2007-188059, in order for the ferrule to be fixed to the holder, it is necessary for the ferrule to be fitted into the holder in a state in which the ferrule is in close contact with the holder without creating a gap between the ferrule and the holder. In this state, the ferrule is fixed to the holder by YAG welding, adhesive, resistance welding, press-fitting, caulking or the like.
When the YAG welding or adhesive is used, a fixing strength between the ferrule and the holder increases as the above gap decreases. Thus, even when the YAG welding or adhesive is used, like when press-fitting is used, the inside diameter of the holder is made smaller than the outside diameter of the ferrule. Then in this state, the ferrule is press-fitted into the holder.
In this press-fitting process, however, a very large load is applied along an axial direction for press-fitting. When the load is applied to the ferrule and the holder, the optical fiber disposed in the ferrule and the optical element disposed in the holder are distorted. Then, the distortion leads to degradation in optical performance.
Particularly, the load for press-fitting increases with an increasing tolerance (interference) between the ferrule and the holder. Accordingly, as described above, distortion is more likely to occur in the optical fiber and optical element and optical performance is further degraded due to a load when an optical device is assembled. Therefore, an optical performance is more degraded due to the load during assembly with an increasing tolerance (interference).